Im 99% certain I had it full, first field of the day and first bird I shot at that day. I think (assuming I had it full) as the carrier lifted the second shell, the carrier latch never engaged and the rest just shot out onto the ground. Im going to test this and see if this is even possible. But the main question is why is the carrier latch occasionally letting a shell out of the tube, onto the carrier. It does not seam to be engaged on the face of the shell very far, maybe a 1/32 of an inch.
I did replace the trigger guard this summer because the other broke in half. I was told that this is a common problem. The trigger guard is what holds all of the trigger, carrier, hammer, cartridge drop lever, etc. If the replacement was bad and not hold the cartridge drop lever out far enough, that would cause the carrier latch to not engage as far. At least to me it looks that way.